Private FER systems and FER systems for private use are, in many cases, systems for transforming solar energy: in recent years, photovoltaic systems have gone through considerable development, mainly because of two factors: very strong incentives, which have made it advantageous for people living in developed countries to invest in such systems, and a significant reduction of the costs incurred for purchasing such systems.
According to prior-art system designs, the production obtained from private photovoltaic systems can be destined to self-consumption, i.e. the energy produced can be consumed directly by the system owner without being fed into a power distribution system, or else it may be fed into the public network via a two-way meter.
Generally, therefore, the energy produced by the FER is measured for a first time by a meter installed downstream of the production system. It is then split into two parts: one part is consumed locally, and the other part is fed into the network. An additional meter is therefore needed for metering the energy fed into the network, generally a public network, by each system.
One very important feature of such systems is that power production is diffused and scattered over the territory. There are a lot of small or very small systems everywhere, an important part thereof being associated with private houses. This new characteristic of electric energy production, which no longer takes place in just a few big power plants, but in a large number of small generation centers, certainly has a very strong impact on the general infrastructures of a country's electric system. In general, the tendency towards an increase in the number of small, distributed energy sources, as opposed to big power plants, is driven by the increased number of FER's, but is not, in theory, limited to FER's only. The scope of the present invention, although referring to the exemplary case of FER's and photovoltaic systems, actually extends to any system for producing electric energy in a local and distributed manner, such as, for example, power production systems utilizing wind, biomass, fossil fuels, etc.
Therefore, the following description will generally refer to generic Local Energy Sources FLE (Fonti Locali di Energia, in Italian).
According to the prior art, therefore, the inclusion layout of a local power production system FLE or FER requires that the energy produced, made available as alternating current, be measured for a first time through a meter performing the function of measuring the total production. Subsequently the energy can be either consumed by a local user or fed into the network of a local energy distributor and sold to the latter. It is clear that the energy exchange with the local distributor is generally a two-way exchange, since the case wherein the surplus energy produced locally is sold to the local distributor is not the only possible one. In fact, it may be the case that the locally produced energy is insufficient to meet the requirements of the local user, so that the latter will have to buy energy from the local distributor. According to the prior-art, in such cases the meter between the local system and the distributor is generally a two-way meter.
For more complex self-consumption requirements, e.g. jointly-owned systems, or more in general for requirements relating to a community of users, a number of problem arise which include the problem of providing a controlled management of self-consumption by single users, who are all individually connected to the network, each with its own meter that measures the power taken from the network, and who must remain connected to the network because they must be allowed to take energy therefrom should local production be insufficient.
Many jointly-owned systems or, more in general, community systems have already been installed, exist and are operational. These are cases wherein a plurality of subjects get organized and make investments in order to create, for example, a suitably sized photovoltaic system. Such a collective investment allows to benefit from economy of scale and, in some cases, from the use of common areas (e.g. the roof of a jointly-owned building).
In typical collective systems of this kind, the system is connected to the network of a distributor (to which also the individual users are, usually but not necessarily, connected). Said distributor takes on the task of absorbing the energy produced by the system and supplying the single users with the energy they need. The balance between produced energy and consumed energy can be done off-line: therefore, there is no actual self-consumption of energy that could be used immediately as it is made available by the generation system, without going through an external distribution system.
The most common prior art offers a very simplistic solution to this problem, in that it exploits the presence of a local distributor to absorb the most part of the electric energy production, possibly with extremely low localized self-consumption, which is only limited to a single user (usually in a co-ownership). This type of management allows to apply the same layout intended for private systems characterized by having a single user to community systems as well.
The prior art does not propose a solution that allows to maximize localized self-consumption for a plurality of users, still in the presence of one or more distributors enabled to absorb and supply energy to the connected users.
With a view of making electric networks evolve into increasingly economical systems, where energy transportation is minimized, and of making consumption centers become more and more autonomous, it is apparent that localized self-consumption is a target that should be pursued. In fact, when energy can be consumed on site as soon as it is produced, savings are attained in terms of transportation, management and storage costs.
The problem that needs to be solved is, therefore, to allow distinct single users belonging to a community to directly consume locally produced energy before such energy is fed into the network of an energy distributor. Such single users must however be connected, by means of independent meters, to an energy distributor capable of meeting their energy requirements whenever local generation is absent or insufficient.
More generally, the problem that needs to be solved is to allow users connected to a generic distributor (or even to different distributors) to join together for coordinated power consumption management, such coordination including direct consumption, and the associated metering, of locally produced energy.
Allocation of energy produced and self-consumed locally must be handled with sufficient flexibility because, when multiple users compete in requesting their share of energy, the available energy must be divided in accordance with each user's rights, since it is generally possible that the users of the community contribute differently to energy production costs.
Finally, it is important that the solution offers the possibility for the community to include (and possibly to exclude) users participating in the production and self-consumption of electric energy. In general, it is important that communities can be modified and expanded without particular limitations: for this reason, it is useful that the solution be based, as far as apparatuses are concerned, on the additional installation of one apparatus for every new user, and that the general layout of the system is scalar and easily upgradable.
Patent JP-2003-134672-A describes a system for managing electric energy produced locally by a group of users. The system allows a plurality of users, each one having subscribed to a power company for power purchase, to jointly own an energy-generating photovoltaic facility, so as to use the generated power according to a fixed share assigned to the group users, or to sell any excess electric energy to the power company. This system aims at ensuring a fixed and fair distribution of the energy made available by the local source in proportion to the rights of each user in the group. When the photovoltaic power system of any user generates a electric energy surplus, the latter is sold to the power company. Given the fixed distribution of the locally generated electric energy among the users, when a user needs more energy he/she will have to purchase it from the network, thus creating a pointless double transit to and fro the network of the power company, with surplus energy produced by one or more users and sold to the power company, and energy returning from the network to a user needing more energy, which leads to higher costs and line losses. Therefore, the system described in the patent does not solve the above-described problems relating to local consumption optimization and energy saving.